Data oep upload enhancements

[jnnr]

These are possible todos taken from #259

• update metadata template (current is 1.5.0
• Use new checking functionality as described in Data oep upload #259 (comment)
• Set metadata
  • Fill in IsAbout (ontological annotation) in script
• How to handle updated data?
  • Notify about existing data on oep and ask if the user wants to overwrite
  • Or: Allow to append. Implement a get_id function?
    Optional non-priority
• Could check locally that data and metadata match using omi.
• Allow to delete tables on oep (oep delete button will come, so this may be obsolete soon)
• Could use one .json to describe several .csv by making use of "resources" entry.